A control system for a power drive section of a three-phase system is disclosed. The control system comprises a positive sequence channel, a negative sequence channel, and a zero sequence channel. The positive sequence channel processes positive sequence error signals, the negative sequence channel processes negative sequence error signals, and the zero sequence channel processes zero sequence error signals. Each sequence channel includes a harmonic repetitive controller, a repetitive controller compensator, and a fundamental frequency controller configured to operate in parallel with the harmonic repetitive controller and repetitive controller compensator. Both the repetitive controller compensator of the negative sequence channel and the repetitive controller compensator of the positive sequence channel are configured with the same, first frequency response. The repetitive controller compensator of the zero sequence channel is configured with a second frequency response that is different from the first frequency response.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A control system for use in controlling a power drive section of a three-phase power system, wherein the three-phase power system is configured to provide phase voltages at a fundamental frequency, the control system comprising: a positive sequence channel configured to process positive sequence error signals in a dq coordinate system, wherein the positive sequence error signals correspond to positive sequences of the phase voltages, wherein the positive sequence channel includes at least one harmonic repetitive controller, at least one repetitive controller compensator, and at least one fundamental frequency controller configured to operate in parallel with the at least one harmonic repetitive controller and the at least one repetitive controller compensator, wherein the repetitive controller compensator of the positive sequence channel is configured with a first frequency response; a negative sequence channel configured to process negative sequence error signals in the dq coordinate system, wherein the negative sequence error signals correspond to negative sequences of the phase voltages, wherein the negative sequence channel includes at least one harmonic repetitive controller, at least one repetitive controller compensator, and at least one fundamental frequency controller configured to operate in parallel with the at least one harmonic repetitive controller and the at least one repetitive controller compensator, wherein the repetitive controller compensator of the negative sequence channel is configured with the first frequency response; and a zero sequence channel configured to process zero sequence error signals in the dq coordinate system, wherein the zero sequence error signals correspond to zero sequences of the phase voltages, wherein the zero sequence channel includes at least one harmonic repetitive controller, at least one repetitive controller compensator, and at least one fundamental frequency controller configured to operate in parallel with the at least one harmonic repetitive controller and the at least one repetitive controller compensator, wherein the repetitive controller compensator of the zero sequence channel is configured with a second frequency response that is different from the first frequency response.
2. The control system of claim 1 , wherein the first frequency response includes a negative notch at a corner frequency of the power drive section in both the positive sequences and negative sequences of the phase voltages.
3. The control system of claim 1 , wherein the second frequency response includes a negative notch at a corner frequency of the power drive section in the zero sequences of the phase voltages.
4. The control system of claim 1 , wherein the at least one fundamental frequency controller of the positive sequence channel and the at least one fundamental frequency controller of the negative sequence channel each have a pole at a frequency below an overshoot frequency of the power drive section.
5. The control system of claim 1 , wherein the at least one fundamental frequency controller of the zero sequence channel has a pole at a frequency above an overshoot frequency of the power drive section.
6. The control system of claim 1 , wherein each repetitive controller compensator has a transfer function of S(z) comprised of a high-pass filter function F high (z), a zero-phase-shift notch-filter function F notch (z), and a low-pass filter function F low (z), wherein the functions F high (z), F notch (z), and F low (z) have a general form of: F high ( z ) = k h ( z - 1 ) z - p h F notch ( z ) = z 2 n + 2 z n + 1 4 z 2 n F low ( z ) = k l ( z - z 1 ) ( z - p l 1 ) ( z - p l 2 ) wherein p h defines a cross-over frequency to compensate for gains of a respective harmonic repetitive controller, k l defines a gain selected to provide unity gain in a low frequency range of the respective harmonic repetitive controller, z l defines a variable selected to provide zero phase delay in a low frequency range of the respective harmonic repetitive controller, p l1 and p l2 define respective poles selected to provide damping in a high frequency range of the respective harmonic repetitive controller, n defines a variable selected to provide a notch effect around a corner frequency of the power drive section for a respective sequence of the phase voltages, k h defines a proportional gain selected based on a gain in a low frequency range of the respective harmonic repetitive controller, and z defines a frequency of the phase voltages.
7. The control system of claim 1 , wherein each fundamental frequency controller has a general transfer function of: C ( z ) = k c ( z - z c ) ( z - 1 ) ( z - p c ) wherein p c defines a pole located selectively above or below an overshoot frequency of the power drive section depending on whether the fundamental frequency is included in the positive, negative, or zero sequence channel, the value of zero z c defines a phase margin, the value of k c defines system robustness and bandwidth, and z defines a frequency of the phase voltages.
8. The control system of claim 1 , wherein the repetitive controller compensator of the positive sequence channel and the repetitive controller compensator of the negative sequence channel are each configured to use a first set of processing parameters, and the repetitive controller compensator of the zero sequence channel is configured to use a second set of processing parameters having at least one parameter that is different from the first set of processing parameters.
9. The control system of claim 1 , wherein the fundamental frequency controller of the positive sequence channel and the fundamental frequency controller of the negative sequence channel are each configured to use a third set of processing parameters, and wherein the fundamental frequency controller of the zero sequence channel is configured to use a fourth set of processing parameters having at least one parameter that is different from the third set of processing parameters.
10. The control system of claim 1 , wherein each repetitive controller compensator comprises a low-pass filter, a notch-filter, and a high-pass filter.
11. The control system of claim 10 , wherein the notch-filter of the repetitive controller compensator of the positive sequence channel and the notch-filter of the repetitive controller compensator of the negative sequence channel have a same frequency and phase response, and wherein the notch-filter of the repetitive controller compensator of the zero sequence channel has a frequency and phase response that differs from the frequency and phase response of the positive sequence channel and the negative sequence channel.
12. The control system of claim 1 , wherein the harmonic repetitive controller of the positive sequence channel is a 6th order harmonic repetitive controller, and wherein the harmonic repetitive controllers of the negative sequence channel and zero sequence channel are 2nd order harmonic repetitive controllers.
13. The control system of claim 1 , wherein each fundamental frequency controller of the positive and negative sequence channels include a two-pole controller having a pole occurring below an overshoot frequency of the power drive section and each frequency controller of the zero sequence channel includes a two-poll controller having a pole occurring above the overshoot frequency of the power drive section.
14. A control system for use in controlling a three-phase power system having a power drive section, wherein the three-phase power system is configured to provide phase voltages at a fundamental frequency, the control system comprising: a positive sequence channel having a first positive sequence sub-channel configured to process d-axis components of a positive sequence error signal to generate corresponding positive sequence d-axis control signals, the positive sequence channel further having a second positive sequence sub-channel configured to process q-axis components of the positive sequence error signal to generate corresponding positive sequence q-axis control signals, wherein the positive sequence error signal corresponds to positive sequences of the phase voltages; a negative sequence channel having a first negative sequence sub-channel configured to process d-axis components of a negative sequence error signal to generate corresponding negative sequence d-axis control signals, the positive sequence channel further having a second negative sequence sub-channel configured to process q-axis components of the negative sequence error signal to generate corresponding negative sequence q-axis control signals, wherein the negative sequence error signal corresponds to negative sequences of the phase voltages; a zero sequence channel having a first zero sequence sub-channel configured to process d-axis components of a zero sequence error signal to generate corresponding positive sequence d-axis control signals, the positive sequence channel further having a second zero sequence sub-channel configured to process q-axis components of the zero sequence error signal to generate corresponding zero sequence q-axis control signals, wherein the zero sequence error signal corresponds to zero sequences of the phase voltages; and wherein each sub-channel of the positive sequence channel, the negative sequence channel, and the zero sequence channel includes, a harmonic repetitive controller, a repetitive controller compensator, and a fundamental frequency controller configured to operate in parallel with the harmonic repetitive controller and the repetitive controller compensator.
15. The control system of claim 14 , wherein each repetitive controller compensator comprises a low-pass filter, a notch-filter, and a high-pass filter.
16. The control system of claim 14 , wherein the harmonic repetitive controllers of the first positive sequence sub-channel and the second positive sequence sub-channel are configured as 6th order harmonic repetitive controllers.
17. The control system of claim 16 , wherein the repetitive controller compensators of the first positive sequence sub-channel, the second positive sequence sub-channel, the first negative sequence sub-channel, and the second negative sequence sub-channel are configured with a frequency response having a negative notch at a corner frequency of the power drive section in both the positive sequences and negative sequences of the phase voltages.
18. The control system of claim 17 , wherein the harmonic repetitive controllers of the first negative sequence sub-channel, the second negative sequence sub-channel, the first zero sequence sub-channel, and the second zero sequence sub-channel are configured as 2nd order harmonic repetitive controllers.
19. The control system of claim 18 , wherein the repetitive controller compensators of the first positive sequence sub-channel, the second positive sequence sub-channel, the first negative sequence sub-channel, and the second negative sequence sub-channel are configured with a frequency response having a negative notch at a corner frequency of the power drive section in both the positive sequences and negative sequences of the phase voltages.
20. A method for controlling a three-phase power system, wherein the three-phase power system is configured to provide phase voltages at a fundamental frequency, the method comprising: processing positive sequence error signals in a dq coordinate system using positive sequence harmonic repetitive control, positive sequence repetitive control compensation, and positive sequence fundamental frequency control to generate corresponding positive sequence control signals, wherein the positive sequence fundamental frequency control is executed in parallel with the positive sequence harmonic repetitive control and the positive sequence repetitive control compensation; processing negative sequence error signals in the dq coordinate system using negative sequence harmonic repetitive control, negative sequence repetitive control compensation, and negative sequence fundamental frequency control to generate corresponding negative sequence control signals, wherein the negative sequence fundamental frequency control is executed in parallel with the negative sequence harmonic repetitive control and the negative sequence repetitive control compensation; and processing zero sequence error signals in the dq coordinate system using zero sequence harmonic repetitive control, zero sequence repetitive control compensation, and zero sequence fundamental frequency control to generate corresponding zero sequence control signals, wherein the zero sequence fundamental frequency control is executed in parallel with the zero sequence harmonic repetitive control and the positive sequence repetitive control compensation.
21. The method of claim 20 , wherein the positive fundamental frequency control and negative fundamental frequency control have a same frequency and phase response, and wherein the zero fundamental frequency control has a frequency and phase response that is different from the frequency and phase response of the positive fundamental frequency control and negative fundamental frequency control.
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March 11, 2013
June 2, 2015
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